Author
Topic: Reading 4.21v from my 5vreg (Read 2435 times)

My current setup allows me to connect a USB cable to my $50 photovores mobo to power it up. I have the negative to the negative, positive to the positive. When I get the voltage reading off the USB cable directly, it reads 5.15v. When I get the voltage reading between ground and the regulated side of my vreg, it shows 4.21v. 4.21v is not enough to run the AT Mega8 right? When I hook up my 6v battery pack and get the regulated reading from my vreg, its 4.55v. That is also not enough to run the At Mega8 correct?

If im not mistaken, the lowest "high" or "1" voltage for square waves is 4.85v, right? and the highest "low" or "0" voltage is .15v? Am I remembering that correctly? And everything else is read as an error?

Does this mean I should replace my vreg?

In the mean time im just going to hook the USBs positive directly to the VCC pin since USBs are already 5v regulated

Can you tell us the make and model of your voltage regulator? When you say you've tried hooking it up to your 6v battery pack, what is the voltage coming out of the battery pack? I ask this because your battery pack may not be supplying 6v!

Most voltage regulators require a minimum voltage to guarantee a consistent output voltage... you may not be supplying it with enough voltage for it to regulate properly.

Although it is not the cause of the problem, please let us know what size and type filter caps you are using on the input and output side.